Text λ provides a way to store and share text information safely, with minimum hassle.
Your data is encrypted in your device, using a strong secret derived from a passphrase that you choose. Without knowing your passphrase, no one can read your data, including Text λ.
Encryption
libsodium is used to encrypt all data. It is a trusted open-source software with a large community of users.
All of Text λ's cryptography related source-code is available at textlambda/cipher.
How safe is it?
Your data is vulnerable when not in encrypted form, which it needs to be be at the time you edit or read. So it is important to use Text λ in a trusted device.
Once your data is encrypted, it can be safely saved anywhere, including unsecure locations. It is extremely unlikely it will be compromised, assuming you pick a good passphrase that is unguessable by others.
Notebook
Data is saved in notebooks. They are similar in concept to traditional paper notebooks.
Each notebook is a single encrypted file, protected by its own passphrase.
A notebook can be synced to Text λ's server for safe-keeping and to support access from multiple devices. The data gets encrypted on your device and Text λ's server will only receive or transmit the encrypted data so it cannot eavesdrop.
Sharing a notebook
You can choose to share your notebook with trusted peers. A common secret is shared, which will be used to encrypt and decrypt data.
Peers can collaborate by syncing data with Text λ's server -- which will only receive or transmit encrypted data so it cannot eavesdrop.
Publishing a notebook - if you want
A notebook, or parts of it, can be published to Text λ's website.
This feature could be used to author blogs or articles that you want to make available publicly.
The software
Text λ is available on MacOs, Windows, Linux and on mobile platforms, Android and iOS.
A command-line utility is also available, that supports most of the features of the main app. If you prefer working on the terminal, you might like it better than the GUI app.